1. Field of the Invention
The present invention relates to an image pickup apparatus capable of picking up a dynamic image or a still image, such as a video camera.
2. Related Background Art
In a digital color camera, in response to depression of a RELEASE button, an object image is exposed onto a solid-state image pickup element such as a CCD or a CMOS sensor for a desired time period. An image signal obtained thereby is converted into a digital signal, and then is subjected to predetermined processing, such as YC processing, to obtain an image signal of a predetermined format. The digital image signal is recorded in a semiconductor memory. The recorded image signal can be read as desired and reproduced as a signal capable of being displayed or printed, and can be output to a monitor or the like to visualize the recorded image.
One example of a technology for a digital color camera is disclosed in Japanese Laid-open Patent Application No. 9-284617. Japanese Laid-open Patent Application No. 9-284617 discloses a technology which, taking into consideration a change in the distance between an image pickup optical system and a photoelectric conversion element and a change in the index of refraction of the image pickup optical system due to temperature change, makes it possible to always record an image in focus irrespective of the ambient temperature.
Japanese Laid-open Patent Application No. 10-145802 discloses a technology used to make a camera thin, where an image pickup screen is divided into a plurality of regions, and an imaging optical system is provided for each of the regions to form a partial image of an object, wherein one object image is formed with regard to each imaging optical system, and object images (the number of which corresponds to the number of the divisions of the image pickup screen), are projected onto an image pickup element. Dividing the image pickup screen into a plurality of regions makes it possible to arrange the respective imaging optical systems close to a solid-state image pickup element.
In a multiple lens type camera disclosed in Japanese Laid-open Patent Application No. 10-145802, change in ambient temperature not only causes a change in the distance between an objective lens and a photoelectric conversion element, and a change in the index of refraction of an image pickup optical system, but also causes a change in the intervals between image pickup optical systems provided with regard to the respective image pickup regions. This results in an unsatisfactory image.
According to one aspect of the present invention, there is provided an image pickup apparatus comprising a plurality of image pickup portions for receiving different wavelength components of object light, and a plurality of integrally formed optical systems for guiding the object light to the plurality of image pickup portions, respectively, the plurality of integrally formed optical systems being constructed so as to satisfy the following relation:
2xc3x97Axc3x97(xcex1Lxe2x88x920.26xc3x9710xe2x88x925)xc3x9720 less than xc2xdP
wherein xcex1L is the coefficient of linear expansion and A is the interval between object images formed by the plurality of image pickup portions. The image pickup apparatus of the present invention can suppress degradation of an image caused by temperature change.
Other aspects of the present invention will become apparent from the following preferred embodiments.